Axial-centrifugal compressor having system for controlling play

Abstract

In an axial-centrifugal compressor, the rotor of which includes an impeller, axial play is controlled by a special air ventilation to the rotor, by a circuit including two parallel arms, flow rates of which are both controlled by respective veins, and moreover the temperature in one of them is changed by a heat exchanger. The ventilation air is thus controlled, both in terms of temperature and flow rate.

The invention claimed is: 
     
       1. An axial centrifugal compressor comprising:
 a rotor including an axial portion and a spread-out portion, the spread-out portion including an impeller of the rotor; and 
 a stator, separated from the rotor by a flow vein, and including an axial portion and a spread-out portion, the axial portions of the rotor and stator being concentric with an axis line and spaced apart by an amount of radial play, and the spread-out portions of the rotor and stator being aligned along the axis line and spaced apart by an amount of axial play, and 
 a ventilation circuit that adjusts the amount of axial play between the spread-out portions of the rotor and stator, the ventilation circuit extending from the stator into a cavity inside the rotor and including:
 a first arm having a first valve that adjusts an opening amount of the first arm, and 
 
 a second arm having a heat exchanger and a second valve that adjusts an opening amount of the second arm. 
 
     
     
       2. The axial centrifugal compressor according to  claim 1 , wherein the first arm and the second arm have a common origin, in a cavity of the stator adjacent the flow vein. 
     
     
       3. The axial centrifugal compressor according to  claim 1 , wherein the second arm is disposed radially outward of the first arm. 
     
     
       4. The axial centrifugal compressor according to  claim 1 , wherein the heat exchanger of the second arm is provided by a section of the second arm passing through an outer cavity of the stator. 
     
     
       5. The axial centrifugal compressor according to  claim 1 , further comprising control circuitry that opens the second valve at a stable cruising speed of the axial centrifugal compressor. 
     
     
       6. The axial centrifugal compressor according to  claim 1 , wherein the cavity extends between a bearing supporting the rotor and the spread-out portion of the rotor. 
     
     
       7. The axial centrifugal compressor according to  claim 1 , wherein the ventilation circuit extends in a radial arm supporting the rotor. 
     
     
       8. The axial centrifugal compressor according to  claim 1 , wherein the amount of axial play between the spread-out portions of the rotor and stator is greater at startup as compared to during cruising. 
     
     
       9. The axial centrifugal compressor according to  claim 1 , wherein other than a common origin in a cavity of the stator, no part of the first arm is included as part of the second arm. 
     
     
       10. The axial centrifugal compressor according to  claim 1 , wherein the first arm and the second arm originate in a cavity of the stator and terminate in the cavity inside the rotor. 
     
     
       11. The axial centrifugal compressor according to  claim 1 , wherein the ventilation circuit adjusts the amount of axial play between the spread-out portions of the rotor and stator by controlling an air flow rate of each of the first arm and the second arm. 
     
     
       12. The axial centrifugal compressor according to  claim 1 , wherein, during startup, the second valve is completely closed so as to prevent air from flowing through the second arm having the heat exchanger. 
     
     
       13. The axial centrifugal compressor according to  claim 1 , wherein the first arm and the second arm include at least one common conduit portion shared therebetween. 
     
     
       14. The axial centrifugal compressor according to  claim 1 , wherein the ventilation circuit originates in a cavity of the stator and terminates in the cavity inside the rotor.